1. Field of Invention
The present invention relates to a power control and management method, and particularly to a power control and management method implemented with an uninterruptible power system (UPS) and a number of servers connected to the UPS.
2. Related Art
To prevent either accidental power interruptions or abnormal levels of power supply, a UPS is usually required for server computers. Generally, a UPS can be divided into an off-line type UPS and an online type UPS. The off-line type UPS usually is cheaper to produce. When the AC power is normally supplied, it is directly delivered to the computer. When there is a power failure, the UPS immediately switches to an internal DC battery that, via a converter, provides AC power to the computer. Because it is activated only when there is power failure, this type of UPS is also called a standby UPS. When there is power failure, the off-line UPS switches from the domestic power source to the internal battery, which usually causes a short interruption at the switch transition time. However, because the capacitors in the switching power supply of the computer system provides sufficient power during the short power interruption, the computer system is not affected during short UPS switch transitions. However, as the power output increases, it becomes increasingly difficult to perform short and stable switch transitions. Therefore, the off-line UPS conventionally has a lower power output. Further, because the off-line UPS is not activated when the domestic power source is generally normal, the computer system is not protected against very sudden abnormal power surges.
In the conventional online UPS, the normal domestic power supply first passes through a charging circuit of the UPS to both deliver power to the computer system and at the same time charge the UPS. When there is power failure, the internal battery provides the required power, and there is no switching event. Therefore, the online UPS does not have the disadvantages of power interruptions, due to switching transitions. Further, because the domestic power first passes through the charging and stabilizing circuit of the UPS, power spikes, surges or other undesired parasitic effects can be filtered out, which allows a more stable operation of the computer system. The online UPS conventionally is more expensive to manufacture, because there is a higher standard requirement for its components.
In addition to provide necessary power to the computer, the UPS can be also connected via a RS232 cable to the computer COM port so as to enable, for example, a UPS management program of the operating system Windows NT to communicate with the UPS. Via this interface, the UPS management program can access to information such as the UPS current power voltage, electric current, frequency, temperature, load capacity, etc. The UPS management program can be also operable to set the UPS to timely switch off or switch on the computer. For example, when an abnormal event occurs, such as a power failure or insufficient battery power, the UPS can consequently inform Windows NT so that the operating system can timely conduct adequate actions. For example, if there is power failure, the operating system can switch off the computer; before the UPS battery is completely empty, a signal can be sent to Windows NT so that the UPS management program can set the execution of a specific program before the computer shutdown and outputs a signal commanding the UPS shutdown after the computer is shut down.
Various disadvantages can be observed in the conventional UPS implementation. When a single UPS is used to supply a number of load systems, a proper power allocation cannot be obtained due to overload of the UPS internal battery. Therefore, each of the load systems usually cannot complete its work and switch off in optimal conditions. In addition, the traditional UPS implementation does not enable a central management of the power use of the load systems and neither allows for an optimal use of the UPS battery power.
Therefore, there is a need for a power control and management method for managing the UPS battery power, alerting the user of the remaining time the UPS battery can sustain, and the service life of the UPS battery. In particular, there is a need for a method that can conduct an optimal power allocation according to the work amount and the priority of the load systems.